The Characterization of PLGA/Small Intestinal Submucosa Composites as Scaffolds for Intervertebral Disc

Abstract:

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In order to application for the tissue engineered intervertebral disc (IVD), we designed
the synthetic/natural hybrid scaffolds with poly(lactide-co-glycolide) (PLGA) and small intestine
submucosa (SIS). SIS has been widely used as a biomaterial because SIS consists of various
collagens and cytokines. SIS, however, possesses disadvantages such as their weak mechanical
properties and uncontrolled degradation. Novel composite scaffolds of PLGA/SIS were
manufactured by simple immersion method of PLGA scaffolds in SIS solution under vacuum. Then
SIS was crosslinked. Also, PLGA scaffolds and SIS sponges were manufactured by solvent
casting/salt leaching and freeze-dried methods, respectively. We evaluated pore structure, porosity,
water absorption ability and cell viability of three types of scaffolds for the application of IVD.

Abstract: This paper compares the characteristics of chondrocyte adhesion on two types of threedimensional
(3-D) scaffold: types A and B. These 3-D scaffolds can be repeatedly constructed with
the same dimensions using microstereolithography, a system that allows the fabrication of predesigned
internal structures, such as pore size and porosity, by stacking the photopolymerized
material. In tissue engineering, chondrocyte adhesion to a scaffold should have a major effect on the
regeneration of cartilage. In this regard, we evaluated chondrocyte adhesion to two types of scaffold
and found that chondrocyte adhesion was better on the type B scaffold than on the type A,
demonstrating the importance of scaffold geometry in chondrocyte adhesion.

Abstract: Porous and bioactive composite scaffolds based on poly ε-caprolactone(PCL) and
hydroxyapatite(HA) were successfully fabricated by solvent casting and salt leaching method. The
scaffolds have interconnected pore structure with pore size ranging from 10μm to 500μm. The pore
size of PCL scaffold and PCL/HA scaffold were similar to that of the salt particles. The pore walls
became thick and the small pores on the surface of macropores were formed as the HA increased.
MTT assay showed that HA content did not affect initial cell attachment in both PCL scaffolds and
PCL/HA scaffolds. The osteoblasts proliferated in both scaffolds, but the cell number was higher in
the PCL/HA composite scaffolds. It was found that the incorporation of hydroxyapatite enhances
bone cell proliferation rather than initial cell attachment in PCL/HA composite scaffolds. The
results suggest that the PCL/HA composite scaffolds have a potential for the bone tissue
engineering applications.

Abstract: We have developed tensile and porous neutralized chitosan scaffold (NCS) whose pore
size was controlled by freezing temperatures. At -70 oC, mean pore size of 112 μm was obtained. At
-196 oC, mean pore size was approximately 70 μm at surface. The scaffold processed at -196 oC
showed homogeneous small pores with structural integrity, which may be more useful as a guidance
dermal scaffold for inward cell migration. The scaffold processed at –70 oC may be more useful for
cell loading scaffold requiring wider pore. Since biodegradability and biocompatibility are crucial
parameters for the development of dermal scaffold, we evaluated the rate of NCS degradation in the
culture medium containing lysozyme by measuring weight loss as well as mean molecular weight of
the scaffold. Approximately 40% weight loss at one week and 70% weight loss at 30 days was
observed, which means that 70% of the scaffold will be degraded and releasable if the wound
microenvironment is similar to the test condition. Again, mean molecular weight of the scaffold
based on gel permeation chromatography was less than 1x105 after 10 day incubation. This result
suggests that degradation of the NCS begins earlier than the observation of gross weight loss. We
also evaluated whether degradation product of NCS are toxic to the human dermal fibroblast or not.
Chitosan oligomer up to 1.0 mg/ml, which corresponds to 10% of the total degradation derivatives
of the NCS, did not affect the viability of the dermal fibroblast based on MTT assay. This result
along with the biodegradation data suggests that the NCS can be developed as suitable dermal
scaffold.

Abstract: The goal of this study was to investigate release tendency of brain-derived neurotrophic
factor (BDNF) from poly(L-lactide-co-glycolide) (PLGA) and small intestine submucosa (SIS)
scaffold prepared by ice-leaching method. A porous scaffold consisting of PLGA and SIS as carrier
of BDNF has been prepared in the presence of ice particle. SEM image of the PLGA/SIS scaffold
showed an interconnected pore structure. The release behavior of BDNF loaded PLGA/SIS scaffold
was examined for 4 weeks period at phosphate buffered saline (PBS, pH 7.4) at 37 oC. The
sustained release of BDNF over 4 weeks was observed from the PLGA/SIS scaffold. These results
indicate that the sustained release of BDNF from PLGA/SIS scaffold can be very useful for
application in the tissue engineering.

Abstract: New hybrid macroporous scaffolds of polycaprolactone (PCL)/tricalcium phosphate (TCP) were developed by taking into account mechanical properties of the bone to be replaced. FTIR spectra indicated the coating of TCP onto the polymer, providing hydrophilic surfaces necessary for cells to attach. As determined by DSC, the depression of PCL melting point suggested a uniform distribution of PCL within the TCP matrix. SEM micrographs revealed pores of irregular shapes varying from 100-200 µm in size in the resultant structures. Indeed, the pore morphology was precisely determined by the leached particles. The scaffolds could tolerate the impact of at least 5.6 kNm2, making them suitable for use as artificial bones of skull, clavicle and ribs. Rat bone stroma attached and survived on the scaffolds, indicating biocompatible of the used materials. Therefore, the prepared scaffolds would be applicable for bone tissue engineering in the near future.